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llvm-mirror/test/CodeGen/BPF/fi_ri.ll
Alexei Starovoitov 2aa98cf3bd [bpf] Avoid extra pointer arithmetic for stack access
For the program like below
struct key_t {
  int pid;
  char name[16];
};
extern void test1(char *);
int test() {
  struct key_t key = {};
  test1(key.name);
  return 0;
}
For key.name, the llc/bpf may generate the below code:
  R1 = R10  // R10 is the frame pointer
  R1 += -24 // framepointer adjustment
  R1 |= 4   // R1 is then used as the first parameter of test1
OR operation is not recognized by in-kernel verifier.

This patch introduces an intermediate FI_ri instruction and
generates the following code that can be properly verified:
  R1 = R10
  R1 += -20

Patch by Yonghong Song <yhs@plumgrid.com>

llvm-svn: 249371
2015-10-06 04:00:53 +00:00

26 lines
725 B
LLVM

; RUN: llc < %s -march=bpf | FileCheck %s
%struct.key_t = type { i32, [16 x i8] }
; Function Attrs: nounwind uwtable
define i32 @test() #0 {
%key = alloca %struct.key_t, align 4
%1 = bitcast %struct.key_t* %key to i8*
; CHECK: mov r1, 0
; CHECK: stw -8(r10), r1
; CHECK: std -16(r10), r1
; CHECK: std -24(r10), r1
call void @llvm.memset.p0i8.i64(i8* %1, i8 0, i64 20, i32 4, i1 false)
; CHECK: mov r1, r10
; CHECK: addi r1, -20
%2 = getelementptr inbounds %struct.key_t, %struct.key_t* %key, i64 0, i32 1, i64 0
; CHECK: call test1
call void @test1(i8* %2) #3
ret i32 0
}
; Function Attrs: nounwind argmemonly
declare void @llvm.memset.p0i8.i64(i8* nocapture, i8, i64, i32, i1) #1
declare void @test1(i8*) #2